Wood fibre debris which develops as a result of storage and handling of logs for use in the primary forest resources manufacturing industries has generally been collected and disposed of in landfill sites, usually adjacent to the primary mills. In the case of sawmills, the traditional means of disposing of the accumulated debris has been by burning it in tee-pee or silo burners. Millions of cubic meters of wood fibre has been disposed of by this means in the last few decades. This is both a pollution source and a waste.
Increased environmental sensitivity to both landfilling and burning is bringing about a change in the forest resources industry. Tighter controls, and the legislated elimination of open burning, have resulted in the industry looking at alternative means for disposal and/or other end uses for this wood fibre debris. One of the logical and obvious alternatives to either burning (tee-pee or silo, non heat recovery) or landfilling is to convert the wood fibre rich debris into a homogeneous hog fuel to fire power boilers. The major problem with this approach is the lack of a market for the hog fuel in areas other than those in close proximity to existing major users. Although there is now significant movement toward the use of this surplus residual debris for fuel to fire cogeneration facilities, this end use is very limited to date and makes up a very small fraction of the gross volume of wood fibre debris available.
With the shrinking virgin fibre basket, it is evident that much more must be done to direct the maximum amount of total fibre harvested into the most appropriate and highest value end uses. It would be a valuable development if more of the normally wasted or misused residual wood fibre debris, which is rich in wood fibre, could be converted to usable pulp chips, as the highest end-value product. To date, no single piece of equipment has been available to economically, efficiently and simultaneously segregate or classify raw wood fibre debris, and effectively remove the bark from the broken log chunks, in preparation for chipping.
In order to process raw wood debris in the field today, using currently available equipment, it would be necessary to first feed the debris from a live bottom hopper to a set of scalping screens to separate different size fractions and then to a debarker such as an apparatus sold by CAE Machinery Ltd. under the trade-mark Fuji King. Large rocks are normally separated from the debris by using gap rolls.